The invention relates to an areal implant and a process for the manufacture of such an implant.
Often, after the intraperitoneal implantation of polymer meshes, adhesions of internal structures occur, such as intestine, omentum, etc. Possibilities have therefore been sought for years of preventing adhesion in the area of the implant, both in the centre and the periphery, or at least to reduce its intensity.
An implant marketed by Gore under the name Dualmesh®, which is not a mesh, but a PTFE membrane, has pores on one side in order to facilitate a better tissue integration. With regard to adhesions, this implant displays favourable behaviour; it is not incorporated sufficiently into the tissue, however.
The Sepramesh® implant from Genzyme is a heavyweight polypropylene mesh which contains a film consisting essentially of natural substances (carboxymethylcellulose and hyaluronic acid) but which is brittle.
Sofradim markets under the name Parietex-Composite® a polyester mesh coated with bovine collagen which has its own problems caused by BSE and proteins not occurring naturally in the body and cannot be cut to size according to the manufacturer's instructions.
U.S. Pat. No. 6,162,962 mentions that implantable polymer meshes can also be strengthened with resorbable films, but discloses no method for the preparation of large-pored meshes which are connected in a sufficiently stable manner to a thin, sensitive, resorbable polymer film. Furthermore, there is no mention of an intraperitoneal application or reference to the reduction of adhesions.
WO 93/17635 shows two-layered composite implants which consist of a porous layer, which is to promote the growing-in of tissue and also to bring about an inflammatory reaction, and a barrier, which is intended to counteract postoperative adhesions.
JP 03295561 discloses films, which contain collagen, have a mesh-like structure and are intended to prevent adhesions.
R. Dinsmore et al. (J. Am. College of Surgeons 191(2), pp. 131-6 (August 2000)) describe the reduction of adhesions with the help of “Seprafilm” (Genzyme), a mixture of a natural product and a modified natural product (hyaluronic acid and carboxymethylcellulose), during the treatment of abdominal wall defects with a polypropylene mesh. “Seprafilm” has the disadvantage that it is relatively brittle when dried and has to be pre-wetted before the surgery.
WO 99/51163 shows resorbable polymer meshes which are covered with different resorbable polymer layers, the second layer being intended to resorb more slowly.
WO 90/00410 describes the reinforcing of polymer films with partly or completely resorbable polymers.
WO 00/67663 discloses a hernia-repair mesh that contains an incision and is covered at one end with a membrane which is intended to prevent the adhesion of the spermatic cord. Such a mesh cannot be used for abdominal wall defects due to the incision and cannot be cut to size everywhere.
U.S. Pat. No. 5,743,917 describes non-resorbable, heavyweight polypropylene meshes customary in the trade, which are covered with a non-resorbable layer of PTFE which is not to be incorporated into the tissue.
WO 01/43789 shows meshes layered with hyaluronic acid and carboxymethylcellulose.